Steel plate lifting tongs



Oct. 17, 1944. J. C. RENFROE STEEL PLATE LIFTING TONGS Filed Aug. 21, 1943 2 Sheets-Sheet 1 Och J. c. RENFROE I STEEL PLATE LIFTING TONGS Filed Aug. 21, 1943 2 Sheets-Sheet 2 J-CIRe'nf Patented Oct. 17, 1944 UNITED- STATES PATENT OFFICE STEEL PLATE LIFTIN G TONGS Joseph C. Renfroe, Jacksonville, Fla. Application August 21, 1943, Serial No. 499,533

2 Claims.

My invention relates to improvements in lifting tongs, and more particularly to a novel construction of steel plate lifting tongs which will be capable of lifting steel plates weighing many tons, and when supported on a lifting cable, will safely and efiiciently transport the steel plate to the desired place on a construction job where it will be welded in place,

An object of my invention is to provide an improved steel plate lifting tongs, which when a steel plate is inserted between a fixed and a cam operated pair of jaws, will upon the raising of a lifting cable attached to the tongs, cause the cam operated jaw to positively grasp the side of the plate while forcing the other side of the plate into the fixed jaw to firmly grasp the plate and to lift the same without any danger of the plate slipping from the tongs and falling to the ground, with the possibility of injuring or killing workmen on the construction job upon which the tongs are employed.

Another object of my invention is to provide an improved steel plate lifting tongs which will be provided with a fixed jaw and pivoted cam jaw, said cam jaw being brought into operation by suitable interconnected linkage when'the lifting cable to which the tongs are attached is raised by a derrick or other suitable means, said tongs being used either in conjunction with or without a manually controlled spring projected cam jaw locking pawl.

A further object of my invention is to provide an improved steel plate lifting tongs capable of lifting steel plates from the ground to a construction job without any danger of dropping the plates in transit, said tongs being highly efiicient in use and relatively inexpensive to manufacture.

Other objects will appear as the description proceeds.

In the accompanying drawings which form a part of my application,

Figure 1 is a vertical sectional view taken through the preferred form of my plate lifting tongs;

Figure 2 is a side elevation on a small scale of my preferred form of steel plate lifting tongs;

Figure 3 is an edge view looking into the end of my preferred form of steel plate lifting tongs;

Figure 4 is a side elevation, partly in section of a slightly modified form of my steel plate lifting tongs;

Figure 5 is a sectional view taken on the line 5-5 on Figure 4, and

' Figure 6 is a sectional view taken on the line 6-5 on Figure 4 of the drawings.

Like characters of reference are used throughout the following specification and the accompanying drawings to designate corresponding parts.

In carrying out my invention, I provide an improved form of steel plate lifting tongs used in transporting or lifting steel plates often weighing many tons from the ground to the side of a ship under construction, where it will be welded in place to form a part of the skin or hull covering of the ship, the construction of the tongs being such that the grasping action will be positive to such a degree that a manual releasing of the tongs will be necessary before the plate may be detached from the tongs.

My invention comprises a tongs body having a pair of spaced body plates I and 2 of substantially inverted U-shape, which are separated by the spacing or filler blocks 3 and 4, all of said parts being held together as an integral unit by means of the body rivets 5 extending through said plates and blocks. It will be understood that the several parts forming my improved tongs will be made from metal, which may be hardened or not, as desired.

A fixed jaw 6 of hardened steel, being substantially T-shaped and formed with a serrated forward plate gripping surface 1, is positioned between the two body plates I and 2 and held fixed thereto by means of the rivets 8 extending through the said jaw and plates, said jaw extending a slight distance into the slot 9 formed in the lower portion of the body proper, as clearly illustrated in Figures 1 and 2 of the drawings. -A pivoted cam jaw I0 is pivoted between the spaced body plates I and 2 on the bearing pin II and is formed with a milled plate engaging cam surface I2 and an adjacent toothed or rack portion I3, which cooperates with a spring pressed locking pawl I4, later to be described. A cross bearing block I5 is mounted between the plates I and 2 and forms a guide for the hollow locking pawl I4, which is formed with a toothed or rack portion I 6, which cooperates with the toothed or rack portion I3 on the cam jaw I 0, under the tension of the coil spring I! which bears against the block I5 and the adjacent surface of the locking pawl M to normally force the rack portions I3 and I6 into engagement with each other. The block I5 is held in place by means of the rivets I3 therethrough and the adjacent plates I and 2. A transversely extending rotary cam roller I9 is mounted between the plates I and 2 and through the upper end of the locking pawl I 4 above the block I5, and is provided on the outside of the plate I, with a manually operated lever 20 which is secured to its outer end. The cam roller I9 is formed with two flat surfaces 2| and 22 at right angles to each other and are so arranged that movement of the lever 20 in a downward direction releases the pawl [4 from contact with the cam jaw 10, while movement of the lever 20 in an upward direction causes the engagement of the pawl M with the cam jaw [0, to lock the same when a steel plate to be lifted is in position between the jaws 6 and It. An operating lever 23 is pivotally mounted on a cross pin 24 between the plates I and 2, and is mounted at its opposite end on the bearing pin 25. A

pair of connecting rods 26 and 21 are mounted on the outside of the plates I and 2, and are connected at their opposite ends with the bearing pin 25, and with the cross bearing pin 28 mounted through the outer arm of the cam jaw ID. The lifting shackle 29 is also mounted on the bearing pin 25, so that when a steel plate in inserted between the jaws 6 and I0, and a lifting cable (not shown) which will be connected with the shackle 29, is raised, the interconnected linkage causes the cam jaw to move inwardly and clamp the adjacent side of the steel plate firmly, and the pawl [4 will then automatically lock the cam jaw ID in fixed position, so that it will be impossible to accidentally drop the steel plate when being moved. A simple movement of the operating lever-20 in a downward direction will cause the immediate release of the cam jaw to release the steel plate.

The modified form of my invention is constructed quite like the preferred form shown in Figures 1, 2 and 3 of the drawings as regards the body and cooperating jaws. A slotted shackle bar 30 is secured to the body plates 3| and 32 to form a filler block between the said plates, and is secured to the plate by means of the rivets 33. The cam jaw locking pawl 34 is pivoted to the lower end of the vertically slidable cam locking rod 35, and is urged in a downward direction by means of the coil spring 36 positioned about the rod 35. Teeth 3'! are formed on the lower end of the pawl 34 and engage teeth 31' on the cam jaw 38. When the locking rod 35 is raised to disengage the pawl 34 from the cam jaw 38, the hooked upper end of the rod will be received withing a locking lip 39 on the shackle bar 30. A cross bearing pin 40 is adapted to slide vertically in the slot in the shackle bar 30 and supports the pair of connecting arms 4| and 42, which are also connected to a cross pin 43 extending through the outer end of the cam jaw 38. A lifting shackle 44 is connected to the ends of the cross bearing pin 40, so that when a lifting cable (not shown) which will be connected with the shackle 44 is raised, the relative movement between the shackle and the linkage and body connected with the shackle, will cause the cam jaw 38 to have a cam movement towards the fixed jaw 6' to engage the object or plate to be lifted, whereupon the locking pawl 34 will lock the cam jaw 38 in locked. position, thus holding the object tightly and without danger of dropping it, until the said object or plate has reached the desired position, and the locking pawl has been manually released.

It will be understood that I do not intend to limit myself to the specific arrangements and constructions shown in the drawings and described in the specification, as many minor changes in detail of construction may be resorted to without departure from the spirit of the invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A lifting tongs having spaced body plates adapted to receive and house a fixed jaw and a cam jaw at the opposite sides, of a slot formed in one edge of said body, locking teeth formed on said cam jaw, a resiliently tensioned toothed locking pawl carried by said body adapted to cooperate with and engage the teeth on the said cam jaw to hold the same in locked position, a lifting shackle having an adjustable contact with said tongs, linkage between said tongs and shackle and between said cam jaw and said shackle whereby when said tongs are lifted by said shackle, the cam jaw will be caused to engage and clamp the object to be lifted which had previously been inserted in the body slot.

2. The subject matter as claimed in claim 1, and means on said shackle adapted to receive the upper end of the locking pawl to hold the same disengaged from the teeth on the cam jaw.

JOSEPH C. RENFROE. 

